Electrically heated annealing furnace



Jan. 11, 1938. w, RQHN 2,104,886

ELECTRICALLY HEATED ANNEALING FURNACE Filed Aug. 7, 1935 INVENTOR I/I/ILHELM oH/v. BY (4 2 g 4 ATTO R N EY-S.

Patented Jan. 11, 1938 UNITED STATES PATENT OFFICE ELECTRICALLY HEATED ANNEALIN G FURNACE many Application August '7, 1935, Serial No. 85,094 In (lemony April 80, 1934 SCIaims.

This invention relates to improvements in electrically heated annealing furnaces, more especially in vertlcaLbright annealing furnaces, for strips with a protective atmosphere.

5 Furnaces of the kind referred to have been described in which the annealing zone is located immediately above the cooling and preheating zone and the material to be treated is passed over a reversing roll arranged in the top portion of the furnace.

The object of the present invention is to provide a furnace of this kind the construction of which involves a very low expense and the substantial parts of which may be easily exchanged.

A furnace according to the invention is illustrated by way of example in the annexed drawing in which Fig. 1 is a vertical section; Fig. 2 is a vertical section in a plane normal to the section of Fig. 1; and Fig. 3 is a horizontal section 90 along plane 3-3 of Figs. 1 and 2.

Referring to these Pigs. 1, 2, and 3, A, B is the casing of the furnace consisting of two concentric sheet metal cylinders, the space between which is filled with a heat-insulating material C. The top end of the furnace is closed by a cover D fitting into a ring shaped oil seal E. P is a filling of heat-insulating material. The reversing roll is secured to the cover by means of a holder H which also supports the heating element J. The strip K to be annealed coming from below, is passed between the inner wall 13 of the casing and the heating element and over the roll 0 and then again on the other side downwards between the heating element J and the wall D.

By the arrangement here described I attain above all that the essential parts of the furnace, viz. the heating element and the reversing roll, may easily be exchanged. These parts, moreover, are relatively small and easy to manufacture. As the casing is constructed as simple as possible, it may be built up even by a smaller factory desiring to erect a bright annealing plant, and the cover carrying the reversing roll and the heating element may-then only be put on this 45 simple casing.

and therefore a smaller total weight of the heating elements will be required and a considerable expense may be saved.

A further advantage consists in that the heat transmission from the heating element to the 5 strip to be annealed is extraordinarily favourable, no structural part intervening between the heating element and the material to be treated.

To recapitulate, the described mode of construction combines a very simple and cheap performance with a very favourable eificiency.

It is especially useful to make the height of the tubular chamber beneath the heating element long enough for an exchange of the heat between the outgoing and the ingoing strip to allow the strip to go out at a sufilciently low temperature to prevent it from oxidation.

I claim:

1. An annealing furnace comprising a vertically sustained elongated chamber open at the top and bottom to the atmosphere and having the vertical side walls thereof insulated against the passage of heat therethrough, a top end closure member detachably secured in end closing position, electrical resistance heating means centrally 25 disposed in the upper end of said chamber, and a roller element horizontally sustained above said heating means centrally within said chamber and depending from said closure member, said roller element being adapted to receive and impart a reverse bend to a metal strip passing thereto through the open bottom of said chamber.

2. The combination of claim 1, said elongated chamber comprising two concentric metal cylinders with the space between the cylinder walls filled with heat insulating material.

3. An annealing furnace comprising a vertically sustained elongated chamber normally closed at the top and open at the bottom to the atmosphere and having vertical side walls thereof insulated against the passage of heat therethrough, electrical resistance heating means suspended from the top and centrally disposed in the upper end of said chamber, a roller element horizontally sustained above said heating means centrally within said chamber adapted to receive and impart a reverse bend to a metal strip passing thereto through the open bottom of said chamber, the space between the portions of the metal strip on opposite sides of said roller being open beneath the heating element for a sumcient distance to permit an exchange of heat between the ingoing and outgoing portions of the strip to allow the strip to go out of the bottom of the chamber at a sufiiciently low temperature to prevent oxidation of the strip.

WILHELM ROHN. 

